Scanning optical beam technologies, such as bar-code readers, cameras, projection TVs, endoscopes, and laparoscopes, often employ miniature electrical-mechanical mirrors, such as micro-electrical-mechanical (MEMS) mirrors, to direct the optical beam. MEMS mirrors typically use high-voltage electrostatic, electrothermal, piezoelectric, or electromagnetic actuation, which all typically require electrical wires attached to the mirror. These wires can block the optical beam, precluding certain optical designs. Additionally, high voltages are considered unsafe and unreliable for certain applications, such as medical devices.
A conventional alternative for medical scanning devices employs an optical fiber to bring in the light and collect the return signal. Theses devices typically rotate the optical fiber within the device to obtain a scanned image. One current approach for creating a circular scan about a rotation axis employs a rotating mechanical linkage driven by an external motor to rotate the optical fiber. This approach suffers from several drawbacks. One drawback is that the rotating mechanical linkage typically requires an expensive component known as an optical rotary connector. Another drawback is that, for narrow bore (<2 mm) scanning instruments, the stiffness of the mechanical train of the instrument is insufficient to ensure uniform rotation of the optical fiber. Non-uniform rotation of the optical fiber leads to distortion of the image, known as Non-Uniform Rotation Distortion (NURD). A further drawback is that this approach produces a single axis scan.
Accordingly, improved approaches for providing miniature optical scanning devices is needed.